Interpretive Summary: Viruses in Gladiolus result in streaking of the flower and cause decreased vigor of the plant. There are no commercial cultivars of Gladiolus that are resistant to virus for breeding so an alternative strategy is to develop virus resistant plants using genetic engineering. A promoter controls both the levels of gene expression and the location where a gene is expressed. One problem encountered when genetic engineering of Gladiolus is that there are no promoters publicly available for use that confer high levels of expression in Gladiolus. Transgenic plants of Gladiolus were developed to contain a polyubiquitin promoter (GUBQ1) that had been isolated from Gladiolus. Initial analysis of a few of these plants show that the polyubiquitin promoter results in the highest levels of gene expression found so far in leaves and roots of Gladiolus. This promoter should be useful for genetic engineering plants of Gladiolus that are virus resistant.

Technical Abstract:
Gladiolus is an important floral crop world wide that is grown in the garden and sold as a cutflower. Bulb crops such as Gladiolus suffer from viruses because they are propagated vegetatively. Viruses in Gladiolus result in streaking of the flower and cause decreased vigor of the plant. There are no commercial cultivars of Gladiolus that are resistant to virus for breeding so an alternative strategy is to develop virus resistant plants using genetic engineering. One problem encountered when genetic engineering of Gladiolus is that the only promoter found to express at high levels is the CaMV 35S promoter. A polyubiquitin promoter isolated from Gladiolus (GUBQ1) has been shown to express at levels comparable to the CaMV 35S promoter in cells following transient transformation. This promoter was tested by transient transformation in other floral crops including Freesia, Lilium (lily), Canna, and Rosa hybrida (rose), and the levels of GUS activity were comparable to the CaMV 35S in freesia and rose. Transgenic Gladiolus plants containing the uidA gene under control of the GUBQ1 promoter have been found to show GUS expression in the leaves, roots, and callus derived from the transgenic plant.